Microencapsulation of Bacillus Mojavensis as potent probiotic strain isolated from soil of Iran and determining characterization

Probiotics are living microbes whose presence in food has beneficial effects for the host by improving the digestive system's microbial flora. Bacterial encapsulation safeguards delicate bacteria from adverse conditions and enhances their stability. Hence, the aim of this research was to isolate resistant Bacillus mojavensis as a probiotic from North East Tehran soil and encapsulated using sodium alginate for increasing its stability. In this study, five soil samples from Jamshidiyeh Park were taken randomly. The soil samples were tested using the serial dilution preparation method and heat treatment to isolate the Bacillus genus exclusively. Following the purification of grown colonies and spore staining, catalase and oxidase tests were performed to confirm the genus of Bacillus sp., and then tests such as acid resistance, salt, bile salt test, and antibiotic resistance were performed to confirm the probiotics of the purified species. In order to determine more precisely the superior genus and species with probiotic characteristics, molecular identification (sequencing 16srRNA) was performed. Next, sodium alginate was used to encapsulate the Bacillus strain. Confirmatory analyzes of microcapsule formation, including photography with an SEM electron microscope and using DLS analysis, were performed to check the confirmation of microcapsule formation, particle size, microcapsule counting, and stability. Overall, we isolated 33 g-positive Bacillus sp., of which 7 strains showed probiotic properties. Ultimately, we selected the strain named (ZK)1 as the indicator strain, exhibiting all probiotic properties. With a 99.8 % similarity rate, 16-srRNA sequencing showed that the target strain belonged to the genus and species Bacillus mojavensis MK764986. The microencapsulation with sodium alginate results confirmed the cells were between 5 and 12 micrometers across and spread out evenly. The study's findings indicated that the country's native soil ecosystem and the Bacillus strains isolated from it serve as a suitable source for the production and introduction of valuable, non-pathogenic native bacteria, serving as a new source of probiotic bacteria. In this research, we found that encapsulated Bacillus sp. can be used in food and pharmaceutical products after proving their probiotic properties because of advantages such as high shelf life.